1
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Bonanno SL, Sanfilippo P, Eamani A, Sampson MM, Kandagedon B, Li K, Burns GD, Makar ME, Zipursky SL, Krantz DE. Constitutive and Conditional Epitope Tagging of Endogenous G-Protein-Coupled Receptors in Drosophila. J Neurosci 2024; 44:e2377232024. [PMID: 38937100 PMCID: PMC11326870 DOI: 10.1523/jneurosci.2377-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/30/2024] [Accepted: 06/06/2024] [Indexed: 06/29/2024] Open
Abstract
To visualize the cellular and subcellular localization of neuromodulatory G-protein-coupled receptors in Drosophila, we implement a molecular strategy recently used to add epitope tags to ionotropic receptors at their endogenous loci. Leveraging evolutionary conservation to identify sites more likely to permit insertion of a tag, we generated constitutive and conditional tagged alleles for Drosophila 5-HT1A, 5-HT2A, 5-HT2B, Oct β 1R, Oct β 2R, two isoforms of OAMB, and mGluR The conditional alleles allow for the restricted expression of tagged receptor in specific cell types, an option not available for any previous reagents to label these proteins. We show expression patterns for these receptors in female brains and that 5-HT1A and 5-HT2B localize to the mushroom bodies (MBs) and central complex, respectively, as predicted by their roles in sleep. By contrast, the unexpected enrichment of Octβ1R in the central complex and of 5-HT1A and 5-HT2A to nerve terminals in lobular columnar cells in the visual system suggest new hypotheses about their functions at these sites. Using an additional tagged allele of the serotonin transporter, a marker of serotonergic tracts, we demonstrate diverse spatial relationships between postsynaptic 5-HT receptors and presynaptic 5-HT neurons, consistent with the importance of both synaptic and volume transmission. Finally, we use the conditional allele of 5-HT1A to show that it localizes to distinct sites within the MBs as both a postsynaptic receptor in Kenyon cells and a presynaptic autoreceptor.
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Affiliation(s)
- Shivan L Bonanno
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Piero Sanfilippo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, California 90095
- Howard Hughes Medical Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095
| | - Aditya Eamani
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Maureen M Sampson
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Binu Kandagedon
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Kenneth Li
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Giselle D Burns
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Marylyn E Makar
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - S Lawrence Zipursky
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, California 90095
- Howard Hughes Medical Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095
| | - David E Krantz
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095
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2
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Thornton-Kolbe EM, Ahmed M, Gordon FR, Sieriebriennikov B, Williams DL, Kurmangaliyev YZ, Clowney EJ. Spatial constraints and cell surface molecule depletion structure a randomly connected learning circuit. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.17.603956. [PMID: 39071296 PMCID: PMC11275898 DOI: 10.1101/2024.07.17.603956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The brain can represent almost limitless objects to "categorize an unlabeled world" (Edelman, 1989). This feat is supported by expansion layer circuit architectures, in which neurons carrying information about discrete sensory channels make combinatorial connections onto much larger postsynaptic populations. Combinatorial connections in expansion layers are modeled as randomized sets. The extent to which randomized wiring exists in vivo is debated, and how combinatorial connectivity patterns are generated during development is not understood. Non-deterministic wiring algorithms could program such connectivity using minimal genomic information. Here, we investigate anatomic and transcriptional patterns and perturb partner availability to ask how Kenyon cells, the expansion layer neurons of the insect mushroom body, obtain combinatorial input from olfactory projection neurons. Olfactory projection neurons form their presynaptic outputs in an orderly, predictable, and biased fashion. We find that Kenyon cells accept spatially co-located but molecularly heterogeneous inputs from this orderly map, and ask how Kenyon cell surface molecule expression impacts partner choice. Cell surface immunoglobulins are broadly depleted in Kenyon cells, and we propose that this allows them to form connections with molecularly heterogeneous partners. This model can explain how developmentally identical neurons acquire diverse wiring identities.
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Affiliation(s)
- Emma M. Thornton-Kolbe
- Neurosciences Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Maria Ahmed
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Finley R. Gordon
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | | | - Donnell L. Williams
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | | | - E. Josephine Clowney
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Michigan Neuroscience Institute, Ann Arbor, MI, USA
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3
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Raja KKB, Yeung K, Li Y, Chen R, Mardon G. A single cell RNA sequence atlas of the early Drosophila larval eye. BMC Genomics 2024; 25:616. [PMID: 38890587 PMCID: PMC11186242 DOI: 10.1186/s12864-024-10423-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 05/16/2024] [Indexed: 06/20/2024] Open
Abstract
The Drosophila eye has been an important model to understand principles of differentiation, proliferation, apoptosis and tissue morphogenesis. However, a single cell RNA sequence resource that captures gene expression dynamics from the initiation of differentiation to the specification of different cell types in the larval eye disc is lacking. Here, we report transcriptomic data from 13,000 cells that cover six developmental stages of the larval eye. Our data show cell clusters that correspond to all major cell types present in the eye disc ranging from the initiation of the morphogenetic furrow to the differentiation of each photoreceptor cell type as well as early cone cells. We identify dozens of cell type-specific genes whose function in different aspects of eye development have not been reported. These single cell data will greatly aid research groups studying different aspects of early eye development and will facilitate a deeper understanding of the larval eye as a model system.
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Affiliation(s)
- Komal Kumar Bollepogu Raja
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Kelvin Yeung
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Graeme Mardon
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
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4
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Smolin N, Dombrovski M, Hina BW, Moreno-Sanchez A, Gossart R, Carmona CR, Rehan A, Hussein RH, Mirshahidi P, Ausborn J, Kurmangaliyev YZ, von Reyn CR. Neuronal identity control at the resolution of a single transcription factor isoform. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.14.598883. [PMID: 38915533 PMCID: PMC11195191 DOI: 10.1101/2024.06.14.598883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
The brain exhibits remarkable neuronal diversity which is critical for its functional integrity. From the sheer number of cell types emerging from extensive transcriptional, morphological, and connectome datasets, the question arises of how the brain is capable of generating so many unique identities. 'Terminal selectors' are transcription factors hypothesized to determine the final identity characteristics in post-mitotic cells. Which transcription factors function as terminal selectors and the level of control they exert over different terminal characteristics are not well defined. Here, we establish a novel role for the transcription factor broad as a terminal selector in Drosophila melanogaster. We capitalize on existing large sequencing and connectomics datasets and employ a comprehensive characterization of terminal characteristics including Perturb-seq and whole-cell electrophysiology. We find a single isoform broad-z4 serves as the switch between the identity of two visual projection neurons LPLC1 and LPLC2. Broad-z4 is natively expressed in LPLC1, and is capable of transforming the transcriptome, morphology, and functional connectivity of LPLC2 cells into LPLC1 cells when perturbed. Our comprehensive work establishes a single isoform as the smallest unit underlying an identity switch, which may serve as a conserved strategy replicated across developmental programs.
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Affiliation(s)
- Natalie Smolin
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA
| | - Mark Dombrovski
- Howard Hughes Medical Institute, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - Bryce W. Hina
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA
| | - Anthony Moreno-Sanchez
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA
| | - Ryan Gossart
- Brandeis University, Department of Biology, Waltham, MA
| | | | - Aadil Rehan
- Howard Hughes Medical Institute, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - Roni H. Hussein
- Howard Hughes Medical Institute, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - Parmis Mirshahidi
- Howard Hughes Medical Institute, Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA
| | - Jessica Ausborn
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA
| | | | - Catherine R. von Reyn
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA
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5
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Prince GS, Reynolds M, Martina V, Sun H. Gene-environmental regulation of the postnatal post-mitotic neuronal maturation. Trends Genet 2024; 40:480-494. [PMID: 38658255 PMCID: PMC11153025 DOI: 10.1016/j.tig.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
Embryonic neurodevelopment, particularly neural progenitor differentiation into post-mitotic neurons, has been extensively studied. While the number and composition of post-mitotic neurons remain relatively constant from birth to adulthood, the brain undergoes significant postnatal maturation marked by major property changes frequently disrupted in neural diseases. This review first summarizes recent characterizations of the functional and molecular maturation of the postnatal nervous system. We then review regulatory mechanisms controlling the precise gene expression changes crucial for the intricate sequence of maturation events, highlighting experience-dependent versus cell-intrinsic genetic timer mechanisms. Despite significant advances in understanding of the gene-environmental regulation of postnatal neuronal maturation, many aspects remain unknown. The review concludes with our perspective on exciting future research directions in the next decade.
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Affiliation(s)
- Gabrielle S Prince
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Molly Reynolds
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Verdion Martina
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - HaoSheng Sun
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL, USA; Freeman Hrabowski Scholar, Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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6
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Liu W, Li Q. Single-cell transcriptomics dissecting the development and evolution of nervous system in insects. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101201. [PMID: 38608931 DOI: 10.1016/j.cois.2024.101201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/14/2024]
Abstract
Insects can display a vast repertoire of complex and adaptive behaviors crucial for survival and reproduction. Yet, how the neural circuits underlying insect behaviors are assembled throughout development and remodeled during evolution remains largely obscure. The advent of single-cell transcriptomics has opened new paths to illuminate these historically intractable questions. Insect behavior is governed by its brain, whose functional complexity is realized through operations across multiple levels, from the molecular and cellular to the circuit and organ. Single-cell transcriptomics enables dissecting brain functions across all these levels and allows tracking regulatory dynamics throughout development and under perturbation. In this review, we mainly focus on the achievements of single-cell transcriptomics in dissecting the molecular and cellular architectures of nervous systems in representative insects, then discuss its applications in tracking the developmental trajectory and functional evolution of insect brains.
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Affiliation(s)
- Weiwei Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China; Yunnan Key Laboratory of Biodiversity Information, Kunming, China.
| | - Qiye Li
- BGI Research, Shenzhen 518083, China; BGI Research, Wuhan 430074, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
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7
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Nern A, Loesche F, Takemura SY, Burnett LE, Dreher M, Gruntman E, Hoeller J, Huang GB, Januszewski M, Klapoetke NC, Koskela S, Longden KD, Lu Z, Preibisch S, Qiu W, Rogers EM, Seenivasan P, Zhao A, Bogovic J, Canino BS, Clements J, Cook M, Finley-May S, Flynn MA, Hameed I, Fragniere AMC, Hayworth KJ, Hopkins GP, Hubbard PM, Katz WT, Kovalyak J, Lauchie SA, Leonard M, Lohff A, Maldonado CA, Mooney C, Okeoma N, Olbris DJ, Ordish C, Paterson T, Phillips EM, Pietzsch T, Salinas JR, Rivlin PK, Schlegel P, Scott AL, Scuderi LA, Takemura S, Talebi I, Thomson A, Trautman ET, Umayam L, Walsh C, Walsh JJ, Xu CS, Yakal EA, Yang T, Zhao T, Funke J, George R, Hess HF, Jefferis GSXE, Knecht C, Korff W, Plaza SM, Romani S, Saalfeld S, Scheffer LK, Berg S, Rubin GM, Reiser MB. Connectome-driven neural inventory of a complete visual system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589741. [PMID: 38659887 PMCID: PMC11042306 DOI: 10.1101/2024.04.16.589741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Vision provides animals with detailed information about their surroundings, conveying diverse features such as color, form, and movement across the visual scene. Computing these parallel spatial features requires a large and diverse network of neurons, such that in animals as distant as flies and humans, visual regions comprise half the brain's volume. These visual brain regions often reveal remarkable structure-function relationships, with neurons organized along spatial maps with shapes that directly relate to their roles in visual processing. To unravel the stunning diversity of a complex visual system, a careful mapping of the neural architecture matched to tools for targeted exploration of that circuitry is essential. Here, we report a new connectome of the right optic lobe from a male Drosophila central nervous system FIB-SEM volume and a comprehensive inventory of the fly's visual neurons. We developed a computational framework to quantify the anatomy of visual neurons, establishing a basis for interpreting how their shapes relate to spatial vision. By integrating this analysis with connectivity information, neurotransmitter identity, and expert curation, we classified the ~53,000 neurons into 727 types, about half of which are systematically described and named for the first time. Finally, we share an extensive collection of split-GAL4 lines matched to our neuron type catalog. Together, this comprehensive set of tools and data unlock new possibilities for systematic investigations of vision in Drosophila, a foundation for a deeper understanding of sensory processing.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Alexandra MC Fragniere
- MRC Laboratory of Molecular Biology, Cambridge, UK and Department of Zoology, University of Cambridge, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Philipp Schlegel
- MRC Laboratory of Molecular Biology, Cambridge, UK and Department of Zoology, University of Cambridge, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Gregory SXE Jefferis
- MRC Laboratory of Molecular Biology, Cambridge, UK and Department of Zoology, University of Cambridge, UK
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8
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Bustillo ME, Douthit J, Astigarraga S, Treisman JE. Two distinct mechanisms of Plexin A function in Drosophila optic lobe lamination and morphogenesis. Development 2024; 151:dev202237. [PMID: 38738602 PMCID: PMC11190435 DOI: 10.1242/dev.202237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 04/28/2024] [Indexed: 05/14/2024]
Abstract
Visual circuit development is characterized by subdivision of neuropils into layers that house distinct sets of synaptic connections. We find that, in the Drosophila medulla, this layered organization depends on the axon guidance regulator Plexin A. In Plexin A null mutants, synaptic layers of the medulla neuropil and arborizations of individual neurons are wider and less distinct than in controls. Analysis of semaphorin function indicates that Semaphorin 1a, acting in a subset of medulla neurons, is the primary partner for Plexin A in medulla lamination. Removal of the cytoplasmic domain of endogenous Plexin A has little effect on the formation of medulla layers; however, both null and cytoplasmic domain deletion mutations of Plexin A result in an altered overall shape of the medulla neuropil. These data suggest that Plexin A acts as a receptor to mediate morphogenesis of the medulla neuropil, and as a ligand for Semaphorin 1a to subdivide it into layers. Its two independent functions illustrate how a few guidance molecules can organize complex brain structures by each playing multiple roles.
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Affiliation(s)
- Maria E. Bustillo
- Department of Cell Biology, New York University Grossman School of Medicine, 435 E. 30th Street, New York, NY 10016, USA
| | - Jessica Douthit
- Department of Cell Biology, New York University Grossman School of Medicine, 435 E. 30th Street, New York, NY 10016, USA
| | - Sergio Astigarraga
- Department of Cell Biology, New York University Grossman School of Medicine, 435 E. 30th Street, New York, NY 10016, USA
| | - Jessica E. Treisman
- Department of Cell Biology, New York University Grossman School of Medicine, 435 E. 30th Street, New York, NY 10016, USA
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9
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Malin JA, Chen YC, Simon F, Keefer E, Desplan C. Spatial patterning controls neuron numbers in the Drosophila visual system. Dev Cell 2024; 59:1132-1145.e6. [PMID: 38531357 PMCID: PMC11078608 DOI: 10.1016/j.devcel.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/18/2023] [Accepted: 03/01/2024] [Indexed: 03/28/2024]
Abstract
Neurons must be made in the correct proportions to communicate with the appropriate synaptic partners and form functional circuits. In the Drosophila visual system, multiple subtypes of distal medulla (Dm) inhibitory interneurons are made in distinct, reproducible numbers-from 5 to 800 per optic lobe. These neurons are born from a crescent-shaped neuroepithelium called the outer proliferation center (OPC), which can be subdivided into specific domains based on transcription factor and growth factor expression. We fate mapped Dm neurons and found that more abundant neural types are born from larger neuroepithelial subdomains, while less abundant subtypes are born from smaller ones. Additionally, morphogenetic Dpp/BMP signaling provides a second layer of patterning that subdivides the neuroepithelium into smaller domains to provide more granular control of cell proportions. Apoptosis appears to play a minor role in regulating Dm neuron abundance. This work describes an underappreciated mechanism for the regulation of neuronal stoichiometry.
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Affiliation(s)
- Jennifer A Malin
- Department of Biology, New York University, New York, NY 10003, USA.
| | - Yen-Chung Chen
- Department of Biology, New York University, New York, NY 10003, USA
| | - Félix Simon
- Department of Biology, New York University, New York, NY 10003, USA
| | - Evelyn Keefer
- Department of Biology, New York University, New York, NY 10003, USA
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA.
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10
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Matsliah A, Yu SC, Kruk K, Bland D, Burke A, Gager J, Hebditch J, Silverman B, Willie K, Willie RW, Sorek M, Sterling AR, Kind E, Garner D, Sancer G, Wernet MF, Kim SS, Murthy M, Seung HS. Neuronal "parts list" and wiring diagram for a visual system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.12.562119. [PMID: 37873160 PMCID: PMC10592826 DOI: 10.1101/2023.10.12.562119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
A catalog of neuronal cell types has often been called a "parts list" of the brain, and regarded as a prerequisite for understanding brain function. In the optic lobe of Drosophila, rules of connectivity between cell types have already proven essential for understanding fly vision. Here we analyze the fly connectome to complete the list of cell types intrinsic to the optic lobe, as well as the rules governing their connectivity. We more than double the list of known types. Most new cell types contain between 10 and 100 cells, and integrate information over medium distances in the visual field. Some existing type families (Tm, Li, and LPi) at least double in number of types. We introduce a new Sm interneuron family, which contains more types than any other, and three new families of cross-neuropil types. Self-consistency of cell types is demonstrated through automatic assignment of cells to types by distance in high-dimensional feature space, and further validation is provided by algorithms that select small subsets of discriminative features. Cell types with similar connectivity patterns divide into clusters that are interpretable in terms of motion, object, and color vision. Our work showcases the advantages of connectomic cell typing: complete and unbiased sampling, a rich array of features based on connectivity, and reduction of the connectome to a drastically simpler wiring diagram of cell types, with immediate relevance for brain function and development.
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Affiliation(s)
| | - Szi-Chieh Yu
- Neuroscience Institute, Princeton University, USA
| | | | - Doug Bland
- Neuroscience Institute, Princeton University, USA
| | - Austin Burke
- Neuroscience Institute, Princeton University, USA
| | - Jay Gager
- Neuroscience Institute, Princeton University, USA
| | | | | | - Kyle Willie
- Neuroscience Institute, Princeton University, USA
| | | | | | | | - Emil Kind
- Institut für Biologie - Neurobiologie, Freie Universität B erlin, Germany
| | - Dustin Garner
- Molecular, Cellular, and Developmental Biology, Univ. C alifornia Santa Barbara, USA
| | - Gizem Sancer
- Institut für Biologie - Neurobiologie, Freie Universität B erlin, Germany
| | - Mathias F Wernet
- Institut für Biologie - Neurobiologie, Freie Universität B erlin, Germany
| | - Sung Soo Kim
- Molecular, Cellular, and Developmental Biology, Univ. C alifornia Santa Barbara, USA
| | - Mala Murthy
- Neuroscience Institute, Princeton University, USA
| | - H Sebastian Seung
- Neuroscience Institute, Princeton University, USA
- Computer Science Department, Princeton University, U SA
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11
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Wang X, Zhai Y, Zheng H. Deciphering the cellular heterogeneity of the insect brain with single-cell RNA sequencing. INSECT SCIENCE 2024; 31:314-327. [PMID: 37702319 DOI: 10.1111/1744-7917.13270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 09/14/2023]
Abstract
Insects show highly complicated adaptive and sophisticated behaviors, including spatial orientation skills, learning ability, and social interaction. These behaviors are controlled by the insect brain, the central part of the nervous system. The tiny insect brain consists of millions of highly differentiated and interconnected cells forming a complex network. Decades of research has gone into an understanding of which parts of the insect brain possess particular behaviors, but exactly how they modulate these functional consequences needs to be clarified. Detailed description of the brain and behavior is required to decipher the complexity of cell types, as well as their connectivity and function. Single-cell RNA-sequencing (scRNA-seq) has emerged recently as a breakthrough technology to understand the transcriptome at cellular resolution. With scRNA-seq, it is possible to uncover the cellular heterogeneity of brain cells and elucidate their specific functions and state. In this review, we first review the basic structure of insect brains and the links to insect behaviors mainly focusing on learning and memory. Then the scRNA applications on insect brains are introduced by representative studies. Single-cell RNA-seq has allowed researchers to classify cell subpopulations within different insect brain regions, pinpoint single-cell developmental trajectories, and identify gene regulatory networks. These developments empower the advances in neuroscience and shed light on the intricate problems in understanding insect brain functions and behaviors.
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Affiliation(s)
- Xiaofei Wang
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Yifan Zhai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and In-sect Pests, Jinan, China
| | - Hao Zheng
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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12
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Sanfilippo P, Kim AJ, Bhukel A, Yoo J, Mirshahidi PS, Pandey V, Bevir H, Yuen A, Mirshahidi PS, Guo P, Li HS, Wohlschlegel JA, Aso Y, Zipursky SL. Mapping of multiple neurotransmitter receptor subtypes and distinct protein complexes to the connectome. Neuron 2024; 112:942-958.e13. [PMID: 38262414 PMCID: PMC10957333 DOI: 10.1016/j.neuron.2023.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/03/2023] [Accepted: 12/20/2023] [Indexed: 01/25/2024]
Abstract
Neurons express various combinations of neurotransmitter receptor (NR) subunits and receive inputs from multiple neuron types expressing different neurotransmitters. Localizing NR subunits to specific synaptic inputs has been challenging. Here, we use epitope-tagged endogenous NR subunits, expansion light-sheet microscopy, and electron microscopy (EM) connectomics to molecularly characterize synapses in Drosophila. We show that in directionally selective motion-sensitive neurons, different multiple NRs elaborated a highly stereotyped molecular topography with NR localized to specific domains receiving cell-type-specific inputs. Developmental studies suggested that NRs or complexes of them with other membrane proteins determine patterns of synaptic inputs. In support of this model, we identify a transmembrane protein selectively associated with a subset of spatially restricted synapses and demonstrate its requirement for synapse formation through genetic analysis. We propose that mechanisms that regulate the precise spatial distribution of NRs provide a molecular cartography specifying the patterns of synaptic connections onto dendrites.
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Affiliation(s)
- Piero Sanfilippo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Alexander J Kim
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anuradha Bhukel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Juyoun Yoo
- Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Pegah S Mirshahidi
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Vijaya Pandey
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Harry Bevir
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ashley Yuen
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Parmis S Mirshahidi
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Peiyi Guo
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Hong-Sheng Li
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yoshinori Aso
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - S Lawrence Zipursky
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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13
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Park YJ, Lu TC, Jackson T, Goodman LD, Ran L, Chen J, Liang CY, Harrison E, Ko C, Hsu AL, Yamamoto S, Qi Y, Bellen HJ, Li H. Whole organism snRNA-seq reveals systemic peripheral changes in Alzheimer's Disease fly models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.10.584317. [PMID: 38559164 PMCID: PMC10979927 DOI: 10.1101/2024.03.10.584317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Peripheral tissues become disrupted in Alzheimer's Disease (AD). However, a comprehensive understanding of how the expression of AD-associated toxic proteins, Aβ42 and Tau, in neurons impacts the periphery is lacking. Using Drosophila, a prime model organism for studying aging and neurodegeneration, we generated the Alzheimer's Disease Fly Cell Atlas (AD-FCA): whole-organism single-nucleus transcriptomes of 219 cell types from adult flies neuronally expressing human Aβ42 or Tau. In-depth analyses and functional data reveal impacts on peripheral sensory neurons by Aβ42 and on various non-neuronal peripheral tissues by Tau, including the gut, fat body, and reproductive system. This novel AD atlas provides valuable insights into potential biomarkers and the intricate interplay between the nervous system and peripheral tissues in response to AD-associated proteins.
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Affiliation(s)
- Ye-Jin Park
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tzu-Chiao Lu
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Tyler Jackson
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Program in Cancer Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lindsey D Goodman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Lindsey Ran
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jiaye Chen
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chung-Yi Liang
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Erin Harrison
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christina Ko
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ao-Lin Hsu
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Department of Internal Medicine, Division of Geriatric and Palliative Medicine, University of Michigan, Ann Arbor, MI 28109, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yanyan Qi
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
- Program in Development, Disease Models & Therapeutics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hongjie Li
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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14
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Zhang Y, Li X. Development of the Drosophila Optic Lobe. Cold Spring Harb Protoc 2024; 2024:108156. [PMID: 37758285 DOI: 10.1101/pdb.top108156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
The Drosophila visual system has been a great model to study fundamental questions in neurobiology, such as neural fate specification, axon guidance, circuit formation, and information processing. The Drosophila visual system is composed of the compound eye and the optic lobe. The optic lobe is divided into four neuropils-namely, the lamina, medulla, lobula, and lobula plate. There are around 200 types of optic lobe neurons, which wire together to form a complex neural structure to processes visual information. These neurons are derived from two neuroepithelial structures-namely, the outer proliferation center (OPC) and the inner proliferation center (IPC), in the larval brain. Recent work on the Drosophila optic lobe has revealed basic principles underlying the development of this complex neural structure, and immunostaining has been a key tool in these studies. Here, we provide a brief overview of the Drosophila optic lobe structure and development, as revealed by immunostaining. First, we introduce the structure of the adult optic lobe. Then, we summarize recent advances in the study of neural fate specification during development of different parts of the optic lobe. Last, we briefly summarize general aspects of axon guidance and neuropil assembly in the optic lobe. With this review, we aim to familiarize readers with this complex neural structure and highlight the power of this great model to study neural development to facilitate further developmental and functional studies using this system.
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Affiliation(s)
- Yu Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Xin Li
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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15
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Ricquebourg R, Konstantinides N. [A temporal mechanism for the generation of neuronal diversity]. Med Sci (Paris) 2024; 40:251-257. [PMID: 38520100 DOI: 10.1051/medsci/2024012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2024] Open
Abstract
One of the greatest challenges in neuroscience is to understand how a complex structure, such as the brain, is built. Spatial and temporal patternings of neuronal progenitors are responsible for the generation of most of the neuronal diversity observed in the brain. This review focuses on the temporal patterning of neuronal progenitors, i.e. the sequential expression of transcription factors that changes the capacity of stem cells to generate different neuronal types, and which is conserved in animals. Recent papers have offered a near complete understanding of the mechanism of temporal patterning in the developing visual system of Drosophila, and of how this contributes to the specification of diverse neuronal identities, which are then maintained by the sustained expression of downstream transcription factors. The insect visual system provides a unique model to study the evolution of neuronal cell types, as well as the evolution of neurodevelopmental mechanisms that generate them.
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16
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Osaka J, Ishii A, Wang X, Iwanaga R, Kawamura H, Akino S, Sugie A, Hakeda-Suzuki S, Suzuki T. Complex formation of immunoglobulin superfamily molecules Side-IV and Beat-IIb regulates synaptic specificity. Cell Rep 2024; 43:113798. [PMID: 38381608 DOI: 10.1016/j.celrep.2024.113798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/03/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
Neurons establish specific synapses based on the adhesive properties of cell-surface proteins while also retaining the ability to form synapses in a relatively non-selective manner. However, comprehensive understanding of the underlying mechanism reconciling these opposing characteristics remains incomplete. Here, we have identified Side-IV/Beat-IIb, members of the Drosophila immunoglobulin superfamily, as a combination of cell-surface recognition molecules inducing synapse formation. The Side-IV/Beat-IIb combination transduces bifurcated signaling with Side-IV's co-receptor, Kirre, and a synaptic scaffold protein, Dsyd-1. Genetic experiments and subcellular protein localization analyses showed the Side-IV/Beat-IIb/Kirre/Dsyd-1 complex to have two essential functions. First, it narrows neuronal binding specificity through Side-IV/Beat-IIb extracellular interactions. Second, it recruits synapse formation factors, Kirre and Dsyd-1, to restrict synaptic loci and inhibit miswiring. This dual function explains how the combinations of cell-surface molecules enable the ranking of preferred interactions among neuronal pairs to achieve synaptic specificity in complex circuits in vivo.
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Affiliation(s)
- Jiro Osaka
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan; Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Arisa Ishii
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Xu Wang
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Riku Iwanaga
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Hinata Kawamura
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Shogo Akino
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Atsushi Sugie
- Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Satoko Hakeda-Suzuki
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan; Research Initiatives and Promotion Organization, Yokohama National University, Yokohama 240-8501, Japan
| | - Takashi Suzuki
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
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17
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Cornean J, Molina-Obando S, Gür B, Bast A, Ramos-Traslosheros G, Chojetzki J, Lörsch L, Ioannidou M, Taneja R, Schnaitmann C, Silies M. Heterogeneity of synaptic connectivity in the fly visual system. Nat Commun 2024; 15:1570. [PMID: 38383614 PMCID: PMC10882054 DOI: 10.1038/s41467-024-45971-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/08/2024] [Indexed: 02/23/2024] Open
Abstract
Visual systems are homogeneous structures, where repeating columnar units retinotopically cover the visual field. Each of these columns contain many of the same neuron types that are distinguished by anatomic, genetic and - generally - by functional properties. However, there are exceptions to this rule. In the 800 columns of the Drosophila eye, there is an anatomically and genetically identifiable cell type with variable functional properties, Tm9. Since anatomical connectivity shapes functional neuronal properties, we identified the presynaptic inputs of several hundred Tm9s across both optic lobes using the full adult female fly brain (FAFB) electron microscopic dataset and FlyWire connectome. Our work shows that Tm9 has three major and many sparsely distributed inputs. This differs from the presynaptic connectivity of other Tm neurons, which have only one major, and more stereotypic inputs than Tm9. Genetic synapse labeling showed that the heterogeneous wiring exists across individuals. Together, our data argue that the visual system uses heterogeneous, distributed circuit properties to achieve robust visual processing.
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Affiliation(s)
- Jacqueline Cornean
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Sebastian Molina-Obando
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Burak Gür
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Annika Bast
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Giordano Ramos-Traslosheros
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jonas Chojetzki
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Lena Lörsch
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Maria Ioannidou
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Rachita Taneja
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Christopher Schnaitmann
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany
| | - Marion Silies
- Institute of Developmental Biology and Neurobiology, Johannes-Gutenberg University, 55128, Mainz, Germany.
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18
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Simon F, Holguera I, Chen YC, Malin J, Valentino P, Erclik T, Desplan C. High-throughput identification of the spatial origins of Drosophila optic lobe neurons using single-cell mRNA-sequencing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.578975. [PMID: 38370610 PMCID: PMC10871188 DOI: 10.1101/2024.02.05.578975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The medulla is the largest neuropil of the Drosophila optic lobe. It contains about 100 neuronal types that have been comprehensively characterized morphologically and molecularly. These neuronal types are specified from a larval neuroepithelium called the Outer Proliferation Center (OPC) via the integration of temporal, spatial, and Notch-driven mechanisms. Although we recently characterized the temporal windows of origin of all medulla neurons, as well as their Notch status, their spatial origins remained unknown. Here, we isolated cells from different OPC spatial domains and performed single-cell mRNA-sequencing to identify the neuronal types produced in these domains. This allowed us to characterize in a high-throughput manner the spatial origins of all medulla neurons and to identify two new spatial subdivisions of the OPC. Moreover, our work shows that the most abundant neuronal types are produced from epithelial domains of different sizes despite being present in a similar number of copies. Combined with our previously published scRNA-seq developmental atlas of the optic lobe, our work opens the door for further studies on how specification factor expression in progenitors impacts gene expression in developing and adult neurons.
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Affiliation(s)
- Félix Simon
- Department of Biology, New York University, New York, NY 10003, USA
| | - Isabel Holguera
- Department of Biology, New York University, New York, NY 10003, USA
| | - Yen-Chung Chen
- Department of Biology, New York University, New York, NY 10003, USA
| | - Jennifer Malin
- Department of Biology, New York University, New York, NY 10003, USA
| | - Priscilla Valentino
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Ted Erclik
- Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Claude Desplan
- Department of Biology, New York University, New York, NY 10003, USA
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19
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Wolterhoff N, Hiesinger PR. Synaptic promiscuity in brain development. Curr Biol 2024; 34:R102-R116. [PMID: 38320473 PMCID: PMC10849093 DOI: 10.1016/j.cub.2023.12.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Precise synaptic connectivity is a prerequisite for the function of neural circuits, yet individual neurons, taken out of their developmental context, readily form unspecific synapses. How does the genome encode brain wiring in light of this apparent contradiction? Synaptic specificity is the outcome of a long series of developmental processes and mechanisms before, during and after synapse formation. How much promiscuity is permissible or necessary at the moment of synaptic partner choice depends on the extent to which prior development restricts available partners or subsequent development corrects initially made synapses. Synaptic promiscuity at the moment of choice can thereby play important roles in the development of precise connectivity, but also facilitate developmental flexibility and robustness. In this review, we assess the experimental evidence for the prevalence and roles of promiscuous synapse formation during brain development. Many well-established experimental approaches are based on developmental genetic perturbation and an assessment of synaptic connectivity only in the adult; this can make it difficult to pinpoint when a given defect or mechanism occurred. In many cases, such studies reveal mechanisms that restrict partner availability already prior to synapse formation. Subsequently, at the moment of choice, factors including synaptic competency, interaction dynamics and molecular recognition further restrict synaptic partners. The discussion of the development of synaptic specificity through the lens of synaptic promiscuity suggests an algorithmic process based on neurons capable of promiscuous synapse formation that are continuously prevented from making the wrong choices, with no single mechanism or developmental time point sufficient to explain the outcome.
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Affiliation(s)
- Neele Wolterhoff
- Division of Neurobiology, Free University Berlin, 14195 Berlin, Germany
| | - P Robin Hiesinger
- Division of Neurobiology, Free University Berlin, 14195 Berlin, Germany.
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20
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Xu C, Ramos TB, Marshall OJ, Doe CQ. Notch signaling and Bsh homeodomain activity are integrated to diversify Drosophila lamina neuron types. eLife 2024; 12:RP90136. [PMID: 38193901 PMCID: PMC10945509 DOI: 10.7554/elife.90136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024] Open
Abstract
Notch signaling is an evolutionarily conserved pathway for specifying binary neuronal fates, yet how it specifies different fates in different contexts remains elusive. In our accompanying paper, using the Drosophila lamina neuron types (L1-L5) as a model, we show that the primary homeodomain transcription factor (HDTF) Bsh activates secondary HDTFs Ap (L4) and Pdm3 (L5) and specifies L4/L5 neuronal fates. Here we test the hypothesis that Notch signaling enables Bsh to differentially specify L4 and L5 fates. We show asymmetric Notch signaling between newborn L4 and L5 neurons, but they are not siblings; rather, Notch signaling in L4 is due to Delta expression in adjacent L1 neurons. While Notch signaling and Bsh expression are mutually independent, Notch is necessary and sufficient for Bsh to specify L4 fate over L5. The NotchON L4, compared to NotchOFF L5, has a distinct open chromatin landscape which allows Bsh to bind distinct genomic loci, leading to L4-specific identity gene transcription. We propose a novel model in which Notch signaling is integrated with the primary HDTF activity to diversify neuron types by directly or indirectly generating a distinct open chromatin landscape that constrains the pool of genes that a primary HDTF can activate.
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Affiliation(s)
- Chundi Xu
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Tyler B Ramos
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Owen J Marshall
- Menzies Institute for Medical Research, University of TasmaniaHobartAustralia
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
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21
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Xu C, Ramos TB, Rogers EM, Reiser MB, Doe CQ. Homeodomain proteins hierarchically specify neuronal diversity and synaptic connectivity. eLife 2024; 12:RP90133. [PMID: 38180023 PMCID: PMC10942767 DOI: 10.7554/elife.90133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
How our brain generates diverse neuron types that assemble into precise neural circuits remains unclear. Using Drosophila lamina neuron types (L1-L5), we show that the primary homeodomain transcription factor (HDTF) brain-specific homeobox (Bsh) is initiated in progenitors and maintained in L4/L5 neurons to adulthood. Bsh activates secondary HDTFs Ap (L4) and Pdm3 (L5) and specifies L4/L5 neuronal fates while repressing the HDTF Zfh1 to prevent ectopic L1/L3 fates (control: L1-L5; Bsh-knockdown: L1-L3), thereby generating lamina neuronal diversity for normal visual sensitivity. Subsequently, in L4 neurons, Bsh and Ap function in a feed-forward loop to activate the synapse recognition molecule DIP-β, thereby bridging neuronal fate decision to synaptic connectivity. Expression of a Bsh:Dam, specifically in L4, reveals Bsh binding to the DIP-β locus and additional candidate L4 functional identity genes. We propose that HDTFs function hierarchically to coordinate neuronal molecular identity, circuit formation, and function. Hierarchical HDTFs may represent a conserved mechanism for linking neuronal diversity to circuit assembly and function.
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Affiliation(s)
- Chundi Xu
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Tyler B Ramos
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
| | - Edward M Rogers
- Janelia Research Campus, Howard Hughes Medical Institute, Helix DriveAshburnUnited States
| | - Michael B Reiser
- Janelia Research Campus, Howard Hughes Medical Institute, Helix DriveAshburnUnited States
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of OregonEugeneUnited States
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22
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Pechmann S. Single-cell expression predicts neuron-specific protein homeostasis networks. Open Biol 2024; 14:230386. [PMID: 38262604 PMCID: PMC10805596 DOI: 10.1098/rsob.230386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 11/17/2023] [Indexed: 01/25/2024] Open
Abstract
The protein homeostasis network keeps proteins in their correct shapes and avoids unwanted aggregation. In turn, the accumulation of aberrantly misfolded proteins has been directly associated with the onset of ageing-associated neurodegenerative diseases such as Alzheimer's and Parkinson's. However, a detailed and rational understanding of how protein homeostasis is achieved in health, and how it can be targeted for therapeutic intervention in diseases remains missing. Here, large-scale single-cell expression data from the Allen Brain Map are analysed to investigate the transcription regulation of the core protein homeostasis network across the human brain. Remarkably, distinct expression profiles suggest specialized protein homeostasis networks with systematic adaptations in excitatory neurons, inhibitory neurons and non-neuronal cells. Moreover, several chaperones and Ubiquitin ligases are found transcriptionally coregulated with genes important for synapse formation and maintenance, thus linking protein homeostasis to the regulation of neuronal function. Finally, evolutionary analyses highlight the conservation of an elevated interaction density in the chaperone network, suggesting that one of the most exciting aspects of chaperone action may yet be discovered in their collective action at the systems level. More generally, our work highlights the power of computational analyses for breaking down complexity and gaining complementary insights into fundamental biological problems.
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23
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Aksamit IC, Dorigão-Guimarães F, Gronenberg W, Godfrey RK. Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps. ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 78:101329. [PMID: 38171085 DOI: 10.1016/j.asd.2023.101329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/13/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024]
Abstract
Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation ("brain soup") method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.
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Affiliation(s)
- Isabel C Aksamit
- Department of Neuroscience, University of Arizona, Tucson, AZ, USA
| | - Felipe Dorigão-Guimarães
- Biodiversity Graduate Program, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences (IBILCE), São José do Rio Preto, SP, Brazil
| | | | - R Keating Godfrey
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA.
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24
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Sun C, Shao Y, Iqbal J. Insect Insights at the Single-Cell Level: Technologies and Applications. Cells 2023; 13:91. [PMID: 38201295 PMCID: PMC10777908 DOI: 10.3390/cells13010091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/23/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Single-cell techniques are a promising way to unravel the complexity and heterogeneity of transcripts at the cellular level and to reveal the composition of different cell types and functions in a tissue or organ. In recent years, advances in single-cell RNA sequencing (scRNA-seq) have further changed our view of biological systems. The application of scRNA-seq in insects enables the comprehensive characterization of both common and rare cell types and cell states, the discovery of new cell types, and revealing how cell types relate to each other. The recent application of scRNA-seq techniques to insect tissues has led to a number of exciting discoveries. Here we provide an overview of scRNA-seq and its application in insect research, focusing on biological applications, current challenges, and future opportunities to make new discoveries with scRNA-seq in insects.
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Affiliation(s)
- Chao Sun
- Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou 310058, China;
| | - Yongqi Shao
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Junaid Iqbal
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
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25
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Wang Y, Liu J, Du LY, Wyss JL, Farrell JA, Schier AF. Gene module reconstruction elucidates cellular differentiation processes and the regulatory logic of specialized secretion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.29.573643. [PMID: 38234833 PMCID: PMC10793473 DOI: 10.1101/2023.12.29.573643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
During differentiation, cells become structurally and functionally specialized, but comprehensive views of the underlying remodeling processes are elusive. Here, we leverage scRNA-seq developmental trajectories to reconstruct differentiation using two secretory tissues as a model system - the zebrafish notochord and hatching gland. First, we present an approach to integrate expression and functional similarities for gene module identification, revealing dozens of gene modules representing known and newly associated differentiation processes and their temporal ordering. Second, we focused on the unfolded protein response (UPR) transducer module to study how general versus cell-type specific secretory functions are regulated. By profiling loss- and gain-of-function embryos, we found that the UPR transcription factors creb3l1, creb3l2, and xbp1 are master regulators of a general secretion program. creb3l1/creb3l2 additionally activate an extracellular matrix secretion program, while xbp1 partners with bhlha15 to activate a gland-specific secretion program. Our study offers a multi-source integrated approach for functional gene module identification and illustrates how transcription factors confer general and specialized cellular functions.
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Affiliation(s)
- Yiqun Wang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
- Biozentrum, University of Basel, Basel, 4056, Switzerland
| | - Jialin Liu
- Biozentrum, University of Basel, Basel, 4056, Switzerland
- Allen Discovery Center for Cell Lineage Tracing, University of Washington, Seattle, WA, 98195, USA
| | - Lucia Y. Du
- Biozentrum, University of Basel, Basel, 4056, Switzerland
- Allen Discovery Center for Cell Lineage Tracing, University of Washington, Seattle, WA, 98195, USA
| | - Jannik L. Wyss
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Jeffrey A. Farrell
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, 20892, USA
| | - Alexander F. Schier
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
- Biozentrum, University of Basel, Basel, 4056, Switzerland
- Allen Discovery Center for Cell Lineage Tracing, University of Washington, Seattle, WA, 98195, USA
- Lead contact
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26
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Bonanno SL, Sanfilippo P, Eamani A, Sampson MM, Binu K, Li K, Burns GD, Makar ME, Zipursky SL, Krantz DE. Constitutive and conditional epitope-tagging of endogenous G protein coupled receptors in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.27.573472. [PMID: 38234787 PMCID: PMC10793450 DOI: 10.1101/2023.12.27.573472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
To visualize the cellular and subcellular localization of neuromodulatory G-protein coupled receptors (GPCRs) in Drosophila , we implement a molecular strategy recently used to add epitope tags to ionotropic receptors at their endogenous loci. Leveraging evolutionary conservation to identify sites more likely to permit insertion of a tag, we generated constitutive and conditional tagged alleles for Drosophila 5-HT1A, 5-HT2A, 5-HT2B, Octβ1R, Octβ2R, two isoforms of OAMB, and mGluR. The conditional alleles allow for the restricted expression of tagged receptor in specific cell types, an option not available for any previous reagents to label these proteins. We show that 5-HT1A and 5-HT2B localize to the mushroom bodies and central complex respectively, as predicted by their roles in sleep. By contrast, the unexpected enrichment of Octβ1R in the central complex and of 5-HT1A and 5-HT2A to nerve terminals in lobular columnar cells in the visual system suggest new hypotheses about their function at these sites. Using an additional tagged allele of the serotonin transporter, a marker of serotonergic tracts, we demonstrate diverse spatial relationships between postsynaptic 5-HT receptors and presynaptic 5-HT neurons, consistent with the importance of both synaptic and volume transmission. Finally, we use the conditional allele of 5-HT1A to show that it localizes to distinct sites within the mushroom bodies as both a postsynaptic receptor in Kenyon cells and a presynaptic autoreceptor. Significance Statement In Drosophila , despite remarkable advances in both connectomic and genomic studies, antibodies to many aminergic GPCRs are not available. We have overcome this obstacle using evolutionary conservation to identify loci in GPCRs amenable to epitope-tagging, and CRISPR/Cas9 genome editing to generated eight novel lines. This method also may be applied to other GPCRs and allows cell-specific expression of the tagged locus. We have used the tagged alleles we generated to address several questions that remain poorly understood. These include the relationship between pre- and post-synaptic sites that express the same receptor, and the use of relatively distant targets by pre-synaptic release sites that may employ volume transmission as well as standard synaptic signaling.
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27
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Carrier Y, Rio LQ, Formicola N, de Sousa-Xavier V, Tabet M, Chen YCD, Wislez M, Orts L, Pinto-Teixeira F. Biased cell adhesion organizes a circuit for visual motion integration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.11.571076. [PMID: 38168373 PMCID: PMC10760042 DOI: 10.1101/2023.12.11.571076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Layer specific computations in the brain rely on neuronal processes establishing synaptic connections with specific partners in distinct laminae. In the Drosophila lobula plate neuropile, the axons of the four subtypes of T4 and T5 visual motion direction-selective neurons segregate into four layers, based on their directional preference, and form synapses with distinct subsets of postsynaptic neurons. Four bi-stratified inhibitory lobula plate intrinsic cells exhibit a consistent synaptic pattern, receiving excitatory T4/T5 inputs in one layer, and conveying inhibitory signals to an adjacent layer. This layered arrangement establishes motion opponency. Here, we identify layer-specific expression of different receptor-ligand pairs belonging to the Beat and Side families of Cell Adhesion Molecules (CAMs) between T4/T5 neurons and their postsynaptic partners. Genetic analysis reveals that Beat/Side mediated interactions are required to restrict T4/T5 axonal innervation to a single layer. We propose that Beat/Side contribute to synaptic specificity by biasing adhesion between synaptic partners before synaptogenesis.
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Affiliation(s)
- Yannick Carrier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Laura Quintana Rio
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Nadia Formicola
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Vicente de Sousa-Xavier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Maha Tabet
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | | | - Maëva Wislez
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Lisa Orts
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Filipe Pinto-Teixeira
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
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28
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Mannino MC, Cassidy MB, Florez S, Rusan Z, Chakraborty S, Schoborg T. Mutations in abnormal spindle disrupt temporal transcription factor expression and trigger immune responses in the Drosophila brain. Genetics 2023; 225:iyad188. [PMID: 37831641 PMCID: PMC10697820 DOI: 10.1093/genetics/iyad188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 08/30/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
The coordination of cellular behaviors during neurodevelopment is critical for determining the form, function, and size of the central nervous system (CNS). Mutations in the vertebrate Abnormal Spindle-Like, Microcephaly Associated (ASPM) gene and its Drosophila melanogaster ortholog abnormal spindle (asp) lead to microcephaly (MCPH), a reduction in overall brain size whose etiology remains poorly defined. Here, we provide the neurodevelopmental transcriptional landscape for a Drosophila model for autosomal recessive primary microcephaly-5 (MCPH5) and extend our findings into the functional realm to identify the key cellular mechanisms responsible for Asp-dependent brain growth and development. We identify multiple transcriptomic signatures, including new patterns of coexpressed genes in the developing CNS. Defects in optic lobe neurogenesis were detected in larval brains through downregulation of temporal transcription factors (tTFs) and Notch signaling targets, which correlated with a significant reduction in brain size and total cell numbers during the neurogenic window of development. We also found inflammation as a hallmark of asp mutant brains, detectable throughout every stage of CNS development, which also contributes to the brain size phenotype. Finally, we show that apoptosis is not a primary driver of the asp mutant brain phenotypes, further highlighting an intrinsic Asp-dependent neurogenesis promotion mechanism that is independent of cell death. Collectively, our results suggest that the etiology of the asp mutant brain phenotype is complex and that a comprehensive view of the cellular basis of the disorder requires an understanding of how multiple pathway inputs collectively determine tissue size and architecture.
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Affiliation(s)
- Maria C Mannino
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Steven Florez
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Zeid Rusan
- Personalis, Inc., Fremont, CA 94555, USA
| | - Shalini Chakraborty
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Todd Schoborg
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
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29
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Lee S, Aubee JI, Lai EC. Regulation of alternative splicing and polyadenylation in neurons. Life Sci Alliance 2023; 6:e202302000. [PMID: 37793776 PMCID: PMC10551640 DOI: 10.26508/lsa.202302000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/06/2023] Open
Abstract
Cell-type-specific gene expression is a fundamental feature of multicellular organisms and is achieved by combinations of regulatory strategies. Although cell-restricted transcription is perhaps the most widely studied mechanism, co-transcriptional and post-transcriptional processes are also central to the spatiotemporal control of gene functions. One general category of expression control involves the generation of multiple transcript isoforms from an individual gene, whose balance and cell specificity are frequently tightly regulated via diverse strategies. The nervous system makes particularly extensive use of cell-specific isoforms, specializing the neural function of genes that are expressed more broadly. Here, we review regulatory strategies and RNA-binding proteins that direct neural-specific isoform processing. These include various classes of alternative splicing and alternative polyadenylation events, both of which broadly diversify the neural transcriptome. Importantly, global alterations of splicing and alternative polyadenylation are characteristic of many neural pathologies, and recent genetic studies demonstrate how misregulation of individual neural isoforms can directly cause mutant phenotypes.
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Affiliation(s)
- Seungjae Lee
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Joseph I Aubee
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Eric C Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, NY, USA
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30
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Ahmed OM, Crocker A, Murthy M. Transcriptional profiling of Drosophila male-specific P1 (pC1) neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566045. [PMID: 37986870 PMCID: PMC10659367 DOI: 10.1101/2023.11.07.566045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
In Drosophila melanogaster, the P1 (pC1) cluster of male-specific neurons both integrates sensory cues and drives or modulates behavioral programs such as courtship, in addition to contributing to a social arousal state. The behavioral function of these neurons is linked to the genes they express, which underpin their capacity for synaptic signaling, neuromodulation, and physiology. Yet, P1 (pC1) neurons have not been fully characterized at the transcriptome level. Moreover, it is unknown how the molecular landscape of P1 (pC1) neurons acutely changes after flies engage in social behaviors, where baseline P1 (pC1) neural activity is expected to increase. To address these two gaps, we use single cell-type RNA sequencing to profile and compare the transcriptomes of P1 (pC1) neurons harvested from socially paired versus solitary male flies. Compared to control transcriptome datasets, we find that P1 (pC1) neurons are enriched in 2,665 genes, including those encoding receptors, neuropeptides, and cell-adhesion molecules (dprs/DIPs). Furthermore, courtship is characterized by changes in ~300 genes, including those previously implicated in regulating behavior (e.g. DopEcR, Octβ3R, Fife, kairos, rad). Finally, we identify a suite of genes that link conspecific courtship with the innate immune system. Together, these data serve as a molecular map for future studies of an important set of higher-order and sexually-dimorphic neurons.
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Affiliation(s)
- Osama M Ahmed
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08540, USA
- Department of Psychology, University of Washington, Seattle, WA 98105, USA
| | - Amanda Crocker
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08540, USA
- Program in Neuroscience, Middlebury College, Middlebury, VT 05753, USA
| | - Mala Murthy
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08540, USA
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31
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Bollepogu Raja KK, Yeung K, Shim YK, Li Y, Chen R, Mardon G. A single cell genomics atlas of the Drosophila larval eye reveals distinct photoreceptor developmental timelines. Nat Commun 2023; 14:7205. [PMID: 37938573 PMCID: PMC10632452 DOI: 10.1038/s41467-023-43037-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
The Drosophila eye is a powerful model system to study the dynamics of cell differentiation, cell state transitions, cell maturation, and pattern formation. However, a high-resolution single cell genomics resource that accurately profiles all major cell types of the larval eye disc and their spatiotemporal relationships is lacking. Here, we report transcriptomic and chromatin accessibility data for all known cell types in the developing eye. Photoreceptors appear as strands of cells that represent their dynamic developmental timelines. As photoreceptor subtypes mature, they appear to assume a common transcriptomic profile that is dominated by genes involved in axon function. We identify cell type maturation genes, enhancers, and potential regulators, as well as genes with distinct R3 or R4 photoreceptor specific expression. Finally, we observe that the chromatin accessibility between cones and photoreceptors is distinct. These single cell genomics atlases will greatly enhance the power of the Drosophila eye as a model system.
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Affiliation(s)
- Komal Kumar Bollepogu Raja
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Kelvin Yeung
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Yoon-Kyung Shim
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Graeme Mardon
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA.
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32
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Sanfilippo P, Kim AJ, Bhukel A, Yoo J, Mirshahidi PS, Pandey V, Bevir H, Yuen A, Mirshahidi PS, Guo P, Li HS, Wohlschlegel JA, Aso Y, Zipursky SL. Mapping of multiple neurotransmitter receptor subtypes and distinct protein complexes to the connectome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.02.560011. [PMID: 37873314 PMCID: PMC10592863 DOI: 10.1101/2023.10.02.560011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Neurons express different combinations of neurotransmitter receptor (NR) subunits and receive inputs from multiple neuron types expressing different neurotransmitters. Localizing NR subunits to specific synaptic inputs has been challenging. Here we use epitope tagged endogenous NR subunits, expansion light-sheet microscopy, and EM connectomics to molecularly characterize synapses in Drosophila. We show that in directionally selective motion sensitive neurons, different multiple NRs elaborated a highly stereotyped molecular topography with NR localized to specific domains receiving cell-type specific inputs. Developmental studies suggested that NRs or complexes of them with other membrane proteins determines patterns of synaptic inputs. In support of this model, we identify a transmembrane protein associated selectively with a subset of spatially restricted synapses and demonstrate through genetic analysis its requirement for synapse formation. We propose that mechanisms which regulate the precise spatial distribution of NRs provide a molecular cartography specifying the patterns of synaptic connections onto dendrites.
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Affiliation(s)
- Piero Sanfilippo
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
- Howard Hughes Medical Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Alexander J Kim
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Anuradha Bhukel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Juyoun Yoo
- Neuroscience Interdepartmental Program, University of California Los Angeles, Los Angeles, CA, USA
| | - Pegah S Mirshahidi
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Vijaya Pandey
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Harry Bevir
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Ashley Yuen
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Parmis S Mirshahidi
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Peiyi Guo
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Hong-Sheng Li
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Yoshinori Aso
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - S Lawrence Zipursky
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
- Howard Hughes Medical Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Lead Contact
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33
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Lago-Baldaia I, Cooper M, Seroka A, Trivedi C, Powell GT, Wilson SW, Ackerman SD, Fernandes VM. A Drosophila glial cell atlas reveals a mismatch between transcriptional and morphological diversity. PLoS Biol 2023; 21:e3002328. [PMID: 37862379 PMCID: PMC10619882 DOI: 10.1371/journal.pbio.3002328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 11/01/2023] [Accepted: 09/08/2023] [Indexed: 10/22/2023] Open
Abstract
Morphology is a defining feature of neuronal identity. Like neurons, glia display diverse morphologies, both across and within glial classes, but are also known to be morphologically plastic. Here, we explored the relationship between glial morphology and transcriptional signature using the Drosophila central nervous system (CNS), where glia are categorised into 5 main classes (outer and inner surface glia, cortex glia, ensheathing glia, and astrocytes), which show within-class morphological diversity. We analysed and validated single-cell RNA sequencing data of Drosophila glia in 2 well-characterised tissues from distinct developmental stages, containing distinct circuit types: the embryonic ventral nerve cord (VNC) (motor) and the adult optic lobes (sensory). Our analysis identified a new morphologically and transcriptionally distinct surface glial population in the VNC. However, many glial morphological categories could not be distinguished transcriptionally, and indeed, embryonic and adult astrocytes were transcriptionally analogous despite differences in developmental stage and circuit type. While we did detect extensive within-class transcriptomic diversity for optic lobe glia, this could be explained entirely by glial residence in the most superficial neuropil (lamina) and an associated enrichment for immune-related gene expression. In summary, we generated a single-cell transcriptomic atlas of glia in Drosophila, and our extensive in vivo validation revealed that glia exhibit more diversity at the morphological level than was detectable at the transcriptional level. This atlas will serve as a resource for the community to probe glial diversity and function.
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Affiliation(s)
- Inês Lago-Baldaia
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Maia Cooper
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Austin Seroka
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, Oregon, United States of America
| | - Chintan Trivedi
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Gareth T. Powell
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Stephen W. Wilson
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Sarah D. Ackerman
- Department of Pathology and Immunology, Brain Immunology and Glia Center, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Vilaiwan M. Fernandes
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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34
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Ju L, Glastad KM, Sheng L, Gospocic J, Kingwell CJ, Davidson SM, Kocher SD, Bonasio R, Berger SL. Hormonal gatekeeping via the blood-brain barrier governs caste-specific behavior in ants. Cell 2023; 186:4289-4309.e23. [PMID: 37683635 PMCID: PMC10807403 DOI: 10.1016/j.cell.2023.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/10/2023] [Accepted: 08/01/2023] [Indexed: 09/10/2023]
Abstract
Here, we reveal an unanticipated role of the blood-brain barrier (BBB) in regulating complex social behavior in ants. Using scRNA-seq, we find localization in the BBB of a key hormone-degrading enzyme called juvenile hormone esterase (Jhe), and we show that this localization governs the level of juvenile hormone (JH3) entering the brain. Manipulation of the Jhe level reprograms the brain transcriptome between ant castes. Although ant Jhe is retained and functions intracellularly within the BBB, we show that Drosophila Jhe is naturally extracellular. Heterologous expression of ant Jhe into the Drosophila BBB alters behavior in fly to mimic what is seen in ants. Most strikingly, manipulation of Jhe levels in ants reprograms complex behavior between worker castes. Our study thus uncovers a remarkable, potentially conserved role of the BBB serving as a molecular gatekeeper for a neurohormonal pathway that regulates social behavior.
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Affiliation(s)
- Linyang Ju
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Karl M Glastad
- Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
| | - Lihong Sheng
- Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Janko Gospocic
- Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Urology and Institute of Neuropathology, Medical Center-University of Freiburg, Freiburg, Germany
| | - Callum J Kingwell
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Shawn M Davidson
- Lewis-Sigler Institute for Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Sarah D Kocher
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA; Lewis-Sigler Institute for Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Roberto Bonasio
- Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Shelley L Berger
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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35
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Yoo J, Dombrovski M, Mirshahidi P, Nern A, LoCascio SA, Zipursky SL, Kurmangaliyev YZ. Brain wiring determinants uncovered by integrating connectomes and transcriptomes. Curr Biol 2023; 33:3998-4005.e6. [PMID: 37647901 DOI: 10.1016/j.cub.2023.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 07/12/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023]
Abstract
Advances in brain connectomics have demonstrated the extraordinary complexity of neural circuits.1,2,3,4,5 Developing neurons encounter the axons and dendrites of many different neuron types and form synapses with only a subset of them. During circuit assembly, neurons express cell-type-specific repertoires comprising many cell adhesion molecules (CAMs) that can mediate interactions between developing neurites.6,7,8 Many CAM families have been shown to contribute to brain wiring in different ways.9,10 It has been challenging, however, to identify receptor-ligand pairs directly matching neurons with their synaptic targets. Here, we integrated the synapse-level connectome of the neural circuit11,12 with the developmental expression patterns7 and binding specificities of CAMs6,13 on pre- and postsynaptic neurons in the Drosophila visual system. To overcome the complexity of neural circuits, we focus on pairs of genetically related neurons that make differential wiring choices. In the motion detection circuit,14 closely related subtypes of T4/T5 neurons choose between alternative synaptic targets in adjacent layers of neuropil.12 This choice correlates with the matching expression in synaptic partners of different receptor-ligand pairs of the Beat and Side families of CAMs. Genetic analysis demonstrated that presynaptic Side-II and postsynaptic Beat-VI restrict synaptic partners to the same layer. Removal of this receptor-ligand pair disrupts layers and leads to inappropriate targeting of presynaptic sites and postsynaptic dendrites. We propose that different Side/Beat receptor-ligand pairs collaborate with other recognition molecules to determine wiring specificities in the fly brain. Combining transcriptomes, connectomes, and protein interactome maps allow unbiased identification of determinants of brain wiring.
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Affiliation(s)
- Juyoun Yoo
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Mark Dombrovski
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Parmis Mirshahidi
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Aljoscha Nern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Samuel A LoCascio
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Yerbol Z Kurmangaliyev
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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36
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Mohana G, Dorier J, Li X, Mouginot M, Smith RC, Malek H, Leleu M, Rodriguez D, Khadka J, Rosa P, Cousin P, Iseli C, Restrepo S, Guex N, McCabe BD, Jankowski A, Levine MS, Gambetta MC. Chromosome-level organization of the regulatory genome in the Drosophila nervous system. Cell 2023; 186:3826-3844.e26. [PMID: 37536338 PMCID: PMC10529364 DOI: 10.1016/j.cell.2023.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 03/31/2023] [Accepted: 07/06/2023] [Indexed: 08/05/2023]
Abstract
Previous studies have identified topologically associating domains (TADs) as basic units of genome organization. We present evidence of a previously unreported level of genome folding, where distant TAD pairs, megabases apart, interact to form meta-domains. Within meta-domains, gene promoters and structural intergenic elements present in distant TADs are specifically paired. The associated genes encode neuronal determinants, including those engaged in axonal guidance and adhesion. These long-range associations occur in a large fraction of neurons but support transcription in only a subset of neurons. Meta-domains are formed by diverse transcription factors that are able to pair over long and flexible distances. We present evidence that two such factors, GAF and CTCF, play direct roles in this process. The relative simplicity of higher-order meta-domain interactions in Drosophila, compared with those previously described in mammals, allowed the demonstration that genomes can fold into highly specialized cell-type-specific scaffolds that enable megabase-scale regulatory associations.
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Affiliation(s)
- Giriram Mohana
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Julien Dorier
- Bioinformatics Competence Center, University of Lausanne, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Xiao Li
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Marion Mouginot
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Rebecca C Smith
- Brain Mind Institute, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Héléna Malek
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Marion Leleu
- Bioinformatics Competence Center, University of Lausanne, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Daniel Rodriguez
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Jenisha Khadka
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Patrycja Rosa
- Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, 02-097 Warsaw, Poland
| | - Pascal Cousin
- Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Christian Iseli
- Bioinformatics Competence Center, University of Lausanne, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Simon Restrepo
- Arcoris bio AG, Lüssirainstrasse 52, 6300 Zug, Switzerland
| | - Nicolas Guex
- Bioinformatics Competence Center, University of Lausanne, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Brian D McCabe
- Brain Mind Institute, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland
| | - Aleksander Jankowski
- Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, 02-097 Warsaw, Poland.
| | - Michael S Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
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Lyu C, Li Z, Luo L. Toward building a library of cell type-specific drivers across developmental stages. Proc Natl Acad Sci U S A 2023; 120:e2312196120. [PMID: 37590431 PMCID: PMC10466085 DOI: 10.1073/pnas.2312196120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Affiliation(s)
- Cheng Lyu
- HHMI, Stanford University, Stanford, CA94305
- Department of Biology, Stanford University, Stanford, CA94305
| | - Zhuoran Li
- HHMI, Stanford University, Stanford, CA94305
- Department of Biology, Stanford University, Stanford, CA94305
| | - Liqun Luo
- HHMI, Stanford University, Stanford, CA94305
- Department of Biology, Stanford University, Stanford, CA94305
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38
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Chen YCD, Chen YC, Rajesh R, Shoji N, Jacy M, Lacin H, Erclik T, Desplan C. Using single-cell RNA sequencing to generate predictive cell-type-specific split-GAL4 reagents throughout development. Proc Natl Acad Sci U S A 2023; 120:e2307451120. [PMID: 37523539 PMCID: PMC10410749 DOI: 10.1073/pnas.2307451120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/03/2023] [Indexed: 08/02/2023] Open
Abstract
Cell-type-specific tools facilitate the identification and functional characterization of the distinct cell types that form the complexity of neuronal circuits. A large collection of existing genetic tools in Drosophila relies on enhancer activity to label different subsets of cells and has been extremely useful in analyzing functional circuits in adults. However, these enhancer-based GAL4 lines often do not reflect the expression of nearby gene(s) as they only represent a small portion of the full gene regulatory elements. While genetic intersectional techniques such as the split-GAL4 system further improve cell-type-specificity, it requires significant time and resources to screen through combinations of enhancer expression patterns. Here, we use existing developmental single-cell RNA sequencing (scRNAseq) datasets to select gene pairs for split-GAL4 and provide a highly efficient and predictive pipeline (scMarco) to generate cell-type-specific split-GAL4 lines at any time during development, based on the native gene regulatory elements. These gene-specific split-GAL4 lines can be generated from a large collection of coding intronic MiMIC/CRIMIC lines or by CRISPR knock-in. We use the developing Drosophila visual system as a model to demonstrate the high predictive power of scRNAseq-guided gene-specific split-GAL4 lines in targeting known cell types, annotating clusters in scRNAseq datasets as well as in identifying novel cell types. Lastly, the gene-specific split-GAL4 lines are broadly applicable to any other Drosophila tissue. Our work opens new avenues for generating cell-type-specific tools for the targeted manipulation of distinct cell types throughout development and represents a valuable resource for the Drosophila community.
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Affiliation(s)
| | - Yen-Chung Chen
- Department of Biology, New York University, New York,NY10003
| | - Raghuvanshi Rajesh
- Department of Biology, New York University, New York,NY10003
- Center for Genomics and Systems Biology, New York University, Abu Dhabi51133, United Arab Emirates
| | - Nathalie Shoji
- Department of Biology, New York University, New York,NY10003
| | - Maisha Jacy
- Department of Biology, New York University, New York,NY10003
| | - Haluk Lacin
- Division of Biological and Biomedical Systems, University of Missouri - Kansas City, Kansas City, MO64110
| | - Ted Erclik
- Department of Biology and Cell, University of Toronto - Mississauga, Mississauga, ONL5L 1C6, Canada
- Department of Systems Biology, University of Toronto - Mississauga, Mississauga, ONL5L 1C6, Canada
| | - Claude Desplan
- Department of Biology, New York University, New York,NY10003
- Center for Genomics and Systems Biology, New York University, Abu Dhabi51133, United Arab Emirates
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Ferreira AAG, Desplan C. An Atlas of the Developing Drosophila Visual System Glia and Subcellular mRNA Localization of Transcripts in Single Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.06.552169. [PMID: 37609218 PMCID: PMC10441313 DOI: 10.1101/2023.08.06.552169] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Glial cells are essential for proper nervous system development and function. To understand glial development and function, we comprehensively annotated glial cells in a single-cell mRNA-sequencing (scRNAseq) atlas of the developing Drosophila visual system. This allowed us to study their developmental trajectories, from larval to adult stages, and to understand how specific types of glia diversify during development. For example, neuropil glia that are initially transcriptionally similar in larvae, split into ensheathing and astrocyte-like glia during pupal stages. Other glial types, such as chiasm glia change gradually during development without splitting into two cell types. The analysis of scRNA-seq allowed us to discover that the transcriptome of glial cell bodies can be distinguished from that of their broken processes. The processes contain distinct enriched mRNAs that were validated in vivo. Therefore, we have identified most glial types in the developing optic lobe and devised a computational approach to identify mRNA species that are localized to cell bodies or cellular processes.
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Affiliation(s)
| | - Claude Desplan
- Department of Biology, New York University, New York, NY, USA
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40
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Bustillo ME, Douthit J, Astigarraga S, Treisman JE. Two distinct mechanisms of Plexin A function in Drosophila optic lobe lamination and morphogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552282. [PMID: 37609142 PMCID: PMC10441316 DOI: 10.1101/2023.08.07.552282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Visual circuit development is characterized by subdivision of neuropils into layers that house distinct sets of synaptic connections. We find that in the Drosophila medulla, this layered organization depends on the axon guidance regulator Plexin A. In plexin A null mutants, synaptic layers of the medulla neuropil and arborizations of individual neurons are wider and less distinct than in controls. Analysis of Semaphorin function indicates that Semaphorin 1a, provided by cells that include Tm5 neurons, is the primary partner for Plexin A in medulla lamination. Removal of the cytoplasmic domain of endogenous Plexin A does not disrupt the formation of medulla layers; however, both null and cytoplasmic domain deletion mutations of plexin A result in an altered overall shape of the medulla neuropil. These data suggest that Plexin A acts as a receptor to mediate morphogenesis of the medulla neuropil, and as a ligand for Semaphorin 1a to subdivide it into layers. Its two independent functions illustrate how a few guidance molecules can organize complex brain structures by each playing multiple roles. Summary statement The axon guidance molecule Plexin A has two functions in Drosophila medulla development; morphogenesis of the neuropil requires its cytoplasmic domain, but establishing synaptic layers through Semaphorin 1a does not.
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41
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Schlegel P, Yin Y, Bates AS, Dorkenwald S, Eichler K, Brooks P, Han DS, Gkantia M, Dos Santos M, Munnelly EJ, Badalamente G, Capdevila LS, Sane VA, Pleijzier MW, Tamimi IFM, Dunne CR, Salgarella I, Javier A, Fang S, Perlman E, Kazimiers T, Jagannathan SR, Matsliah A, Sterling AR, Yu SC, McKellar CE, Costa M, Seung HS, Murthy M, Hartenstein V, Bock DD, Jefferis GSXE. Whole-brain annotation and multi-connectome cell typing quantifies circuit stereotypy in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.27.546055. [PMID: 37425808 PMCID: PMC10327018 DOI: 10.1101/2023.06.27.546055] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The fruit fly Drosophila melanogaster combines surprisingly sophisticated behaviour with a highly tractable nervous system. A large part of the fly's success as a model organism in modern neuroscience stems from the concentration of collaboratively generated molecular genetic and digital resources. As presented in our FlyWire companion paper 1 , this now includes the first full brain connectome of an adult animal. Here we report the systematic and hierarchical annotation of this ~130,000-neuron connectome including neuronal classes, cell types and developmental units (hemilineages). This enables any researcher to navigate this huge dataset and find systems and neurons of interest, linked to the literature through the Virtual Fly Brain database 2 . Crucially, this resource includes 4,552 cell types. 3,094 are rigorous consensus validations of cell types previously proposed in the hemibrain connectome 3 . In addition, we propose 1,458 new cell types, arising mostly from the fact that the FlyWire connectome spans the whole brain, whereas the hemibrain derives from a subvolume. Comparison of FlyWire and the hemibrain showed that cell type counts and strong connections were largely stable, but connection weights were surprisingly variable within and across animals. Further analysis defined simple heuristics for connectome interpretation: connections stronger than 10 unitary synapses or providing >1% of the input to a target cell are highly conserved. Some cell types showed increased variability across connectomes: the most common cell type in the mushroom body, required for learning and memory, is almost twice as numerous in FlyWire as the hemibrain. We find evidence for functional homeostasis through adjustments of the absolute amount of excitatory input while maintaining the excitation-inhibition ratio. Finally, and surprisingly, about one third of the cell types proposed in the hemibrain connectome could not yet be reliably identified in the FlyWire connectome. We therefore suggest that cell types should be defined to be robust to inter-individual variation, namely as groups of cells that are quantitatively more similar to cells in a different brain than to any other cell in the same brain. Joint analysis of the FlyWire and hemibrain connectomes demonstrates the viability and utility of this new definition. Our work defines a consensus cell type atlas for the fly brain and provides both an intellectual framework and open source toolchain for brain-scale comparative connectomics.
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42
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Dorkenwald S, Matsliah A, Sterling AR, Schlegel P, Yu SC, McKellar CE, Lin A, Costa M, Eichler K, Yin Y, Silversmith W, Schneider-Mizell C, Jordan CS, Brittain D, Halageri A, Kuehner K, Ogedengbe O, Morey R, Gager J, Kruk K, Perlman E, Yang R, Deutsch D, Bland D, Sorek M, Lu R, Macrina T, Lee K, Bae JA, Mu S, Nehoran B, Mitchell E, Popovych S, Wu J, Jia Z, Castro M, Kemnitz N, Ih D, Bates AS, Eckstein N, Funke J, Collman F, Bock DD, Jefferis GS, Seung HS, Murthy M. Neuronal wiring diagram of an adult brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.27.546656. [PMID: 37425937 PMCID: PMC10327113 DOI: 10.1101/2023.06.27.546656] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Connections between neurons can be mapped by acquiring and analyzing electron microscopic (EM) brain images. In recent years, this approach has been applied to chunks of brains to reconstruct local connectivity maps that are highly informative, yet inadequate for understanding brain function more globally. Here, we present the first neuronal wiring diagram of a whole adult brain, containing 5×107 chemical synapses between ~130,000 neurons reconstructed from a female Drosophila melanogaster. The resource also incorporates annotations of cell classes and types, nerves, hemilineages, and predictions of neurotransmitter identities. Data products are available by download, programmatic access, and interactive browsing and made interoperable with other fly data resources. We show how to derive a projectome, a map of projections between regions, from the connectome. We demonstrate the tracing of synaptic pathways and the analysis of information flow from inputs (sensory and ascending neurons) to outputs (motor, endocrine, and descending neurons), across both hemispheres, and between the central brain and the optic lobes. Tracing from a subset of photoreceptors all the way to descending motor pathways illustrates how structure can uncover putative circuit mechanisms underlying sensorimotor behaviors. The technologies and open ecosystem of the FlyWire Consortium set the stage for future large-scale connectome projects in other species.
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Affiliation(s)
- Sven Dorkenwald
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - Arie Matsliah
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Amy R Sterling
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Eyewire, Boston, USA
| | - Philipp Schlegel
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Szi-chieh Yu
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | | | - Albert Lin
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Center for the Physics of Biological Function, Princeton University, Princeton, USA
| | - Marta Costa
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Katharina Eichler
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Yijie Yin
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - Will Silversmith
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | | | - Chris S. Jordan
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | | | - Akhilesh Halageri
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Kai Kuehner
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | | | - Ryan Morey
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Jay Gager
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | | | | | - Runzhe Yang
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - David Deutsch
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Department of Neurobiology, University of Haifa, Haifa, Israel
| | - Doug Bland
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Marissa Sorek
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Eyewire, Boston, USA
| | - Ran Lu
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Thomas Macrina
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - Kisuk Lee
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Brain & Cognitive Sciences Department, Massachusetts Institute of Technology, Cambridge, USA
| | - J. Alexander Bae
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Electrical and Computer Engineering Department, Princeton University, Princeton, USA
| | - Shang Mu
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Barak Nehoran
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - Eric Mitchell
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Sergiy Popovych
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - Jingpeng Wu
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Zhen Jia
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Manuel Castro
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Nico Kemnitz
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Dodam Ih
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
| | - Alexander Shakeel Bates
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
- Harvard Medical School, Boston, USA
- Centre for Neural Circuits and Behaviour, The University of Oxford, Oxford, UK
| | - Nils Eckstein
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, USA
| | - Jan Funke
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, USA
| | | | - Davi D. Bock
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, USA
| | - Gregory S.X.E Jefferis
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
- Drosophila Connectomics Group, Department of Zoology, University of Cambridge, Cambridge, UK
| | - H. Sebastian Seung
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
- Computer Science Department, Princeton University, Princeton, USA
| | - Mala Murthy
- Princeton Neuroscience Institute, Princeton University, Princeton, USA
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Hopkins BR, Barmina O, Kopp A. A single-cell atlas of the sexually dimorphic Drosophila foreleg and its sensory organs during development. PLoS Biol 2023; 21:e3002148. [PMID: 37379332 DOI: 10.1371/journal.pbio.3002148] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 05/03/2023] [Indexed: 06/30/2023] Open
Abstract
To respond to the world around them, animals rely on the input of a network of sensory organs distributed throughout the body. Distinct classes of sensory organs are specialized for the detection of specific stimuli such as strain, pressure, or taste. The features that underlie this specialization relate both to the neurons that innervate sensory organs and the accessory cells they comprise. To understand the genetic basis of this diversity of cell types, both within and between sensory organs, we performed single-cell RNA sequencing on the first tarsal segment of the male Drosophila melanogaster foreleg during pupal development. This tissue displays a wide variety of functionally and structurally distinct sensory organs, including campaniform sensilla, mechanosensory bristles, and chemosensory taste bristles, as well as the sex comb, a recently evolved male-specific structure. In this study, we characterize the cellular landscape in which the sensory organs reside, identify a novel cell type that contributes to the construction of the neural lamella, and resolve the transcriptomic differences among support cells within and between sensory organs. We identify the genes that distinguish between mechanosensory and chemosensory neurons, resolve a combinatorial transcription factor code that defines 4 distinct classes of gustatory neurons and several types of mechanosensory neurons, and match the expression of sensory receptor genes to specific neuron classes. Collectively, our work identifies core genetic features of a variety of sensory organs and provides a rich, annotated resource for studying their development and function.
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Affiliation(s)
- Ben R Hopkins
- Department of Evolution and Ecology, University of California, Davis, California, United States of America
| | - Olga Barmina
- Department of Evolution and Ecology, University of California, Davis, California, United States of America
| | - Artyom Kopp
- Department of Evolution and Ecology, University of California, Davis, California, United States of America
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44
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Bonanno SL, Krantz DE. Transcriptional changes in specific subsets of Drosophila neurons following inhibition of the serotonin transporter. Transl Psychiatry 2023; 13:226. [PMID: 37355701 DOI: 10.1038/s41398-023-02521-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/06/2023] [Accepted: 06/13/2023] [Indexed: 06/26/2023] Open
Abstract
The transcriptional effects of SSRIs and other serotonergic drugs remain unclear, in part due to the heterogeneity of postsynaptic cells, which may respond differently to changes in serotonergic signaling. Relatively simple model systems such as Drosophila afford more tractable microcircuits in which to investigate these changes in specific cell types. Here, we focus on the mushroom body, an insect brain structure heavily innervated by serotonin and comprised of multiple different but related subtypes of Kenyon cells. We use fluorescence-activated cell sorting of Kenyon cells, followed by either bulk or single-cell RNA sequencing to explore the transcriptomic response of these cells to SERT inhibition. We compared the effects of two different Drosophila Serotonin Transporter (dSERT) mutant alleles as well as feeding the SSRI citalopram to adult flies. We find that the genetic architecture associated with one of the mutants contributed to significant artefactual changes in expression. Comparison of differential expression caused by loss of SERT during development versus aged, adult flies, suggests that changes in serotonergic signaling may have relatively stronger effects during development, consistent with behavioral studies in mice. Overall, our experiments revealed limited transcriptomic changes in Kenyon cells, but suggest that different subtypes may respond differently to SERT loss-of-function. Further work exploring the effects of SERT loss-of-function in other circuits may be used help to elucidate how SSRIs differentially affect a variety of different neuronal subtypes both during development and in adults.
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Affiliation(s)
- Shivan L Bonanno
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - David E Krantz
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA.
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Mohylyak I, Bengochea M, Pascual-Caro C, Asfogo N, Fonseca-Topp S, Danda N, Atak ZK, De Waegeneer M, Plaçais PY, Preat T, Aerts S, Corti O, de Juan-Sanz J, Hassan BA. Developmental transcriptional control of mitochondrial homeostasis is required for activity-dependent synaptic connectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.11.544500. [PMID: 37333418 PMCID: PMC10274921 DOI: 10.1101/2023.06.11.544500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
During neuronal circuit formation, local control of axonal organelles ensures proper synaptic connectivity. Whether this process is genetically encoded is unclear and if so, its developmental regulatory mechanisms remain to be identified. We hypothesized that developmental transcription factors regulate critical parameters of organelle homeostasis that contribute to circuit wiring. We combined cell type-specific transcriptomics with a genetic screen to discover such factors. We identified Telomeric Zinc finger-Associated Protein (TZAP) as a temporal developmental regulator of neuronal mitochondrial homeostasis genes, including Pink1 . In Drosophila , loss of dTzap function during visual circuit development leads to loss of activity-dependent synaptic connectivity, that can be rescued by Pink1 expression. At the cellular level, loss of dTzap/TZAP leads to defects in mitochondrial morphology, attenuated calcium uptake and reduced synaptic vesicle release in fly and mammalian neurons. Our findings highlight developmental transcriptional regulation of mitochondrial homeostasis as a key factor in activity-dependent synaptic connectivity.
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Santos-França PL, David LA, Kassem F, Meng XQ, Cayouette M. Time to see: How temporal identity factors specify the developing mammalian retina. Semin Cell Dev Biol 2023; 142:36-42. [PMID: 35760728 DOI: 10.1016/j.semcdb.2022.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/30/2022]
Abstract
Understanding how retinal progenitor cells (RPCs) give rise to the variety of neural cell types of the retina has been a question of major interest over the last few decades. While environmental cues and transcription factor networks have been shown to control specific cell fate decisions, how RPCs alter fate output over time to control proper histogenesis remains poorly understood. In recent years, the identification of "temporal identity factors (TIFs)", which control RPC competence states to ensure that the right cell types are produced at the right time, has contributed to increasing our understanding of temporal patterning in the retina. Here, we review the different TIFs identified to date in the mammalian retina and discuss the underlying mechanisms by which they are thought to operate. We conclude by speculating on how identification of temporal patterning mechanisms might support the development of new therapeutic approaches against visual impairments.
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Affiliation(s)
- Pedro L Santos-França
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Molecular Biology Program, Université de Montréal, Montréal, QC, Canada
| | - Luke Ajay David
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Integrated Program in Neuroscience, Faculty of Medicine, McGill University, Montréal, QC, Canada
| | - Fatima Kassem
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Integrated Program in Neuroscience, Faculty of Medicine, McGill University, Montréal, QC, Canada
| | - Xiang Qi Meng
- Integrated Program in Neuroscience, Faculty of Medicine, McGill University, Montréal, QC, Canada
| | - Michel Cayouette
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Molecular Biology Program, Université de Montréal, Montréal, QC, Canada; Integrated Program in Neuroscience, Faculty of Medicine, McGill University, Montréal, QC, Canada; Department of Medicine, Université de Montréal, QC, Canada; Department of Anatomy and Cell Biology and Division of Experimental Medicine, McGill University, Montreal, QC, Canada.
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El-Danaf RN, Rajesh R, Desplan C. Temporal regulation of neural diversity in Drosophila and vertebrates. Semin Cell Dev Biol 2023; 142:13-22. [PMID: 35623984 DOI: 10.1016/j.semcdb.2022.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
Abstract
The generation of neuronal diversity involves temporal patterning mechanisms by which a given progenitor sequentially produces multiple cell types. Several parallels are evident between the brain development programs of Drosophila and vertebrates, such as the successive emergence of specific cell types and the use of combinations of transcription factors to specify cell fates. Furthermore, cell-extrinsic cues such as hormones and signaling pathways have also been shown to be regulatory modules of temporal patterning. Recently, transcriptomic and epigenomic studies using large single-cell sequencing datasets have provided insights into the transcriptional dynamics of neurogenesis in the Drosophila and mammalian central nervous systems. We review these commonalities in the specification of neuronal identity and highlight the conserved or convergent strategies of brain development by discussing temporal patterning mechanisms found in flies and vertebrates.
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Affiliation(s)
- Rana N El-Danaf
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
| | - Raghuvanshi Rajesh
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Claude Desplan
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, Abu Dhabi, United Arab Emirates; Department of Biology, New York University, New York, NY 10003, USA.
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48
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Sen SQ. Generating neural diversity through spatial and temporal patterning. Semin Cell Dev Biol 2023; 142:54-66. [PMID: 35738966 DOI: 10.1016/j.semcdb.2022.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 11/19/2022]
Abstract
The nervous system consists of a vast diversity of neurons and glia that are accurately assembled into functional circuits. What are the mechanisms that generate these diverse cell types? During development, an epithelial sheet with neurogenic potential is initially regionalised into spatially restricted domains of gene expression. From this, pools of neural stem cells (NSCs) with distinct molecular profiles and the potential to generate different neuron types, are specified. These NSCs then divide asymmetrically to self-renew and generate post-mitotic neurons or glia. As NSCs age, they experience transitions in gene expression, which further allows them to generate different neurons or glia over time. Versions of this general template of spatial and temporal patterning operate during the development of different parts of different nervous systems. Here, I cover our current knowledge of Drosophila brain and optic lobe development as well as the development of the vertebrate cortex and spinal cord within the framework of this above template. I highlight where our knowledge is lacking, where mechanisms beyond these might operate, and how the emergence of new technologies might help address unanswered questions.
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Affiliation(s)
- Sonia Q Sen
- Tata Institute for Genetics and Society, UAS-GKVK Campus, Bellary Road, Bangalore, India.
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49
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Currier TA, Pang MM, Clandinin TR. Visual processing in the fly, from photoreceptors to behavior. Genetics 2023; 224:iyad064. [PMID: 37128740 PMCID: PMC10213501 DOI: 10.1093/genetics/iyad064] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 03/22/2023] [Indexed: 05/03/2023] Open
Abstract
Originally a genetic model organism, the experimental use of Drosophila melanogaster has grown to include quantitative behavioral analyses, sophisticated perturbations of neuronal function, and detailed sensory physiology. A highlight of these developments can be seen in the context of vision, where pioneering studies have uncovered fundamental and generalizable principles of sensory processing. Here we begin with an overview of vision-guided behaviors and common methods for probing visual circuits. We then outline the anatomy and physiology of brain regions involved in visual processing, beginning at the sensory periphery and ending with descending motor control. Areas of focus include contrast and motion detection in the optic lobe, circuits for visual feature selectivity, computations in support of spatial navigation, and contextual associative learning. Finally, we look to the future of fly visual neuroscience and discuss promising topics for further study.
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Affiliation(s)
- Timothy A Currier
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michelle M Pang
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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50
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Wu T, Deger JM, Ye H, Guo C, Dhindsa J, Pekarek BT, Al-Ouran R, Liu Z, Al-Ramahi I, Botas J, Shulman JM. Tau polarizes an aging transcriptional signature to excitatory neurons and glia. eLife 2023; 12:e85251. [PMID: 37219079 PMCID: PMC10259480 DOI: 10.7554/elife.85251] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 05/22/2023] [Indexed: 05/24/2023] Open
Abstract
Aging is a major risk factor for Alzheimer's disease (AD), and cell-type vulnerability underlies its characteristic clinical manifestations. We have performed longitudinal, single-cell RNA-sequencing in Drosophila with pan-neuronal expression of human tau, which forms AD neurofibrillary tangle pathology. Whereas tau- and aging-induced gene expression strongly overlap (93%), they differ in the affected cell types. In contrast to the broad impact of aging, tau-triggered changes are strongly polarized to excitatory neurons and glia. Further, tau can either activate or suppress innate immune gene expression signatures in a cell-type-specific manner. Integration of cellular abundance and gene expression pinpoints nuclear factor kappa B signaling in neurons as a marker for cellular vulnerability. We also highlight the conservation of cell-type-specific transcriptional patterns between Drosophila and human postmortem brain tissue. Overall, our results create a resource for dissection of dynamic, age-dependent gene expression changes at cellular resolution in a genetically tractable model of tauopathy.
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Affiliation(s)
- Timothy Wu
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Medical Scientist Training Program, Baylor College of MedicineHoustonUnited States
| | - Jennifer M Deger
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Medical Scientist Training Program, Baylor College of MedicineHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
| | - Hui Ye
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Department of Neurology, Baylor College of MedicineHoustonUnited States
| | - Caiwei Guo
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
| | - Justin Dhindsa
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Medical Scientist Training Program, Baylor College of MedicineHoustonUnited States
| | - Brandon T Pekarek
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Rami Al-Ouran
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Department of Pediatrics, Baylor College of MedicineHoustonUnited States
- Center for Alzheimer’s and Neurodegenerative Diseases, Baylor College of MedicineHoustonUnited States
| | - Ismael Al-Ramahi
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Center for Alzheimer’s and Neurodegenerative Diseases, Baylor College of MedicineHoustonUnited States
| | - Juan Botas
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Center for Alzheimer’s and Neurodegenerative Diseases, Baylor College of MedicineHoustonUnited States
| | - Joshua M Shulman
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
- Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
- Department of Neurology, Baylor College of MedicineHoustonUnited States
- Center for Alzheimer’s and Neurodegenerative Diseases, Baylor College of MedicineHoustonUnited States
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